TI samples a pre-production chip for grid battery diagnostics

A connector can change the signal engineers use to judge a battery cell. At Texas Instruments, Henrik Mannesson’s team is working around that problem as the company samples the BQ79826Z-Q1, a pre-production monitor that puts Electrochemical Impedance Spectroscopy (EIS)—a way to test a cell’s electrical response—directly on the chip.

The challenge is particularly sharp with lithium iron phosphate (LFP), the chemistry that has become dominant in stationary storage because of its cycle life and safety profile. Its voltage curve is extremely flat through the middle of its state of charge, so a lower voltage can reflect either temporary charge conditions or permanent aging. Conventional battery-management systems estimate the difference from voltage readings and cycle-counting algorithms rather than measuring it directly.

EIS takes a more active route. The chip injects an alternating-current or voltage perturbation into the cell, then measures internal alternating-current impedance across several frequencies. Mannesson told ESS News that the resulting electrical model can separate state of charge from chemical degradation such as lithium plating. The measurement is delicate: wiring, connectors and internal resistance can all affect the result, which is why TI supplies reference designs, evaluation modules and graphical interfaces before customers begin multi-week thermal and degradation tests.

The chip also changes the hardware arithmetic in larger battery packs. It monitors up to 26 cells in series, eight more than competing monitors, while storage systems are moving from 52-cell modules toward 104-cell architectures. Four of the new chips can cover a 104-cell module, potentially minimizing bill of materials, board space and cost per channel. The direct impedance data could also let software teams run their own diagnostic algorithms instead of licensing specialized third-party software.

So what, concretely? For system designers, the proposed gain is cleaner cell-health data without bulky add-on diagnostic hardware. For project funders, better aging and thermal-runaway data could support the reliability evidence behind a storage project’s financing. The limits are clear: the chip is still pre-production, its integration depends on customers, TI expects full volume production only by the end of 2026, and the first commercial systems using it may ship as early as 2027.